Hot melt calendered or extruded wear layer for embossed substrates and method of manufacture

ABSTRACT

The invention relates to a textured surface covering having a hot melt wear layer and methods of applying the hot melt wear layer to a textured or embossed surface without distortion of the visual image of the textured substrate. The wear layer substantially follows the contours of the substrate with minimum change in thickness of the wear layer over the textured surface and provides an aesthetically pleasing three dimensional appearance to the textured surface of the substrate. Melt applying the melt processable polymer resin to the textured substrate with a conformable pressure roll deter entrapment of bubbles between the wear layer and the textured substrate. Therefore, the wear layer exhibits significant clarity and visual depth, as well as improved maintenance (cleanability) properties. The resulting product has a visual image clarity reflecting any texture in the substrate including very light reflective (lenticular moray) embossings.

FIELD OF THE INVENTION

[0001] The present invention relates to decorative products that aresuitable as surface coverings for floors, walls, etc., and, moreparticularly it is directed to an embossed or textured product having awear layer with a substantially uniform thickness and the method ofmanufacturing the rear layer. The wear layer is applied to an embossedor textured substrate and uniquely follows the contours of the substrateto provide a unique three dimensional aesthetic appearance with enhancedclarity.

HISTORICAL BACKGROUND OF THE INVENTION

[0002] Decorative products useful as surface coverings for floors,walls, etc., are well known in the art and have achieved broad use indomestic and commercial environments. Unfortunately, the application ofa protective surface layer on an embossed substrate has presented manydifficult problems. The embossing tends to diminish or distort uponapplication of the wear layer. Such distortion or diminishing reducesthe aesthetic appearance and the three dimensional effect desired.Further, air is entrapped between the wear layer and embossed ortextured substrate when the wear layer is laminated to an embossed ortextured substrate by conventional lamination processes.

[0003] Many prior art protective wear layer surfaces comprise relativelyrigid thermoset polymers which are laminated to a flat substrate. Thelaminated wear layer and substrate is then embossed. For example, SawkaU.S. Pat. No. 5,405,675 discloses applying a substantially uniformlythick protective surface layer to a base layer or substrate and thenembossing the base layer at a temperature between the softeningtemperature of the base layer and the decomposition temperature of thebase layer, but less than the softening temperature of the wear layer.

[0004] Attention is also called to Fry U.S. Pat. No. 4,614,556. In thispatent the wear layer has a relief pattern formed thereon and islaminated to a flat base layer. In another embodiment, the wear layer,which is substantially uniform in thickness, is embossed and then thebase layer comprising a hot-melt composition is applied to the embossedwear layer.

[0005] Other commercially available floor structures are made byapplying a liquid plastisol to a smooth or textured substrate. When theplastisol is fused, air bubbles are entrapped reducing clarity. Further,the liquid plastisol tends to flow into the depressions of the embossedsubstrate, reducing the texture of the exposed surface.

OBJECTS AND SUMMARY OF THE INVENTION

[0006] It is an object of this invention to provide a decorative surfacecovering for floors, walls, etc., which has a subtle textured appearanceproviding new visual and physical three dimensional properties withenhanced clarity.

[0007] Another object of this invention is to provide a textured productwhich visually retains all of the textured features of the substratewhile providing protection by means of the wear layer.

[0008] Still another object of this invention is to provide a wear layeron an embossed or textured substrate which is substantially uniform inthickness with substantially no variation in wear layer thicknessthroughout its length and breadth.

[0009] Yet a further object of this invention is to provide a texturedproduct which clearly reflects the texture of the substrate includingfine lenticular embossing.

[0010] Still a further object of this invention is to provide a directhot melt calendering process or an indirect hot melt calender process inwhich a melt processable polymer resin or hot melt calendered film isformed and applied to woven fabrics, burlap, fibers, caning and scrimsthat have textured properties without evidence of detrimental airentrapment while retaining a visual image of the textured material.

[0011] A further object of this invention is to provide a hot meltcalendering process and wear layer which can be applied to a texturedsubstrate without shade change which normally occurs with plastisolwetting out a fabric or paper substrate.

[0012] Still a further object of this invention is to provide a uniquetextured material and method of producing the same which can be readilymanufactured with commercially available calendering equipment.

[0013] Another object of this invention is the application of a hot meltwear layer to the textured or embossed substrate without loss ofsharpness and distinctiveness and the softening of the embossedsubstrate which can cause a deterioration of the embossed pattern.

[0014] Yet another object of this invention is to permit pre-embossing(chemically and/or mechanically) of a substrate prior to applying a wearlayer, which allows for a range of additional decorating techniques.

[0015] In summary, this invention relates to a hot melt calendered orextruded wear layer which can be melt applied to an embossed or texturedsubstrate without distorting the substrate and which wear layer conformsto the embossing or texture to give a three dimensional aestheticallypleasing product.

[0016] These and other objects of the invention will be apparent fromthe following description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a schematic representation of one preferred embodimentof the equipment and process of the present invention.

[0018]FIG. 2 is a schematic representation of a second preferredembodiment of the equipment and process of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0019] In general, this invention relates to the unique combination ofvisual and physical properties achieved by applying a hot meltcalendered or extruded PVC or non-PVC wear layer to a texturedsubstrate.

[0020] Typical applications of this technology are floor and wallcovering products.

[0021] A variety of textured substrates have been used such as, but notlimited to, woven fabrics, burlap, duck, linens, decorative papers,fibers, scrims, caning and various types of embossed vinyl or embossedfoams. The embossed vinyl or foam can be created either chemicallyand/or mechanically. These textured substrates can also be decorated viagravure printing, screen printing, spray printing or other means toenhance the decorative image.

[0022] The melt processable layer can be formed and applied via meltcalender equipment in widths limited only by equipment and substrateavailability. Referring to FIG. 1, a melt processable polymer resincomposition 1 is delivered as a molten extrudate to a three rollcalender 2 between first roll 3 and second roll 4. The melt processablepolymer resin composition is further softened in the three roll calenderby the heated rolls. The thickness of the molten layer 5 is determinedby the gap between the second roll 4 and the third roll 6.

[0023] An embossed or textured substrate 7 is preheated by a heater 8.The molten layer 5 is applied to the preheated substrate 7 between thethird roll 6 and the conformable pressure roll 9 forming texturedmultilayered composite 10 in which the melt processable polymer resincomposition forms a substantially uniformly thick wear layer. Theconformable pressure roll deters air entrapment between the meltprocessable polymer resin composition and the textured substrate. Theexposed surface of the wear layer closely follows the embossing ortexture of the substrate.

[0024] Referring to FIG. 2, an indirect process is shown in which thehot melt composition or melt processable polymer resin is introduced asa film 11. The film 11 is subsequently melted or softened and applied tothe substrate with a calender, including a two roll calender, or heateddrum and conformable pressure roll, such as a rubber roll.

[0025] In FIG. 2, the film 11 is introduced to a conformable rubberpressure roll 12 and onto a heated drum 13 in such a manner to eliminateentrapment of air between the film 11 and drum 13. The film is heated bythe drum to melt the film or a softened condition approaching melt. Thetextured substrate 14 is preheated by heater 15. The film is then meltapplied to the preheated substrate 14 between the heated drum 13 and asecond rubber pressure roll 16 forming textured multilayered composite17.

[0026] The melt calendered layer can have a wide range of thicknessdepending on cost and performance capabilities desired. Typicalthickness may range from a few mils (0.005″) to very thick layers(0.050″ or greater). The thickness of the layer varies less than 25%with a preferred variation of less than 20%. The difference in height ofthe pre-textured surface of the present invention is at least about 1mil vertical distance in not more than 20 mils horizontal distance,preferably at least about 2 mils vertical distance in not more than 20mils horizontal distance, and the more preferably at least about 5 milsvertical distance in not more than 20 mils horizontal distance.

[0027] The average thickness of the overlying wear layer is betweenabout 2 mils to about 50 mils. The preferred thickness is between about5 mils to about 30 mils, and the most preferred is between about 10 milsto about 20 mils.

[0028] Melt calendering a melt processable layer directly to thetextured substrate can be achieved without the air entrapment normallyassociated with lamination of a transparent layer onto an embossed ortextured substrate by use of a conformable, preferably rubber, pressureroll.

[0029] Adhesive coatings may need to be applied to some substrates inorder to provide adequate adhesion of the composite layers.

[0030] It has been determined that there are critical aspects to thisinvention relating to the viscosity of the hot melt calendered wearlayer. The viscosity must be within a range of 4,500 to 70,000 poise.Above 70,000 poise the applied hot melt wear layer will not adhereadequately to the substrate and the temperature necessary for theviscosity to be below 4,500 poise will cause the hot melt filmcomposition to degrade. The viscosity is measured on an InstronCapillary Rheometer with a ram speed of 0.5 inches per minute and the0.9960 inch long, 0.5033 inch diameter capillary or a shear rate of 73per second.

[0031] For typical melt processable compositions, the specifiedviscosity range corresponds to a temperature range of 425° F. to 225° F.The preferred range is 10,000 to 50,000 poise (375° F. to 295° F.). Inthis range the melt composition bonds well to the substrate and it flowsto conform well to the embossed substrate while substantiallymaintaining a uniform thickness. The most preferred range is 13,000 to24,000 poise which corresponds to 325° F. to 360° F. The applied hotmelt composition cools rapidly on the substrate avoiding distortion ofthe substrate resin though the melt temperature of the substrate may besimilar to that of the hot melt composition which is applied.

[0032] The pre-textured substrate may comprise a layer of a wovenfibrous layer, or a non-woven fibrous layer, or an embossed layer, or alayer comprising deposited matter and combinations thereof, such as afoamable ink or non-foamable ink. In any case, the temperature ofdistortion or melt of the pre-textured resin substrate need not begreater than that of the melt processable composition applied thereto.The viscosity of the melt processable composition is critical. Theviscosity and the temperature associated therewith and rapid coolingpermit the wear layer to conform to the textured substrate without itflowing around and into the valleys of the embossed substrate to give asubstantially uniform wear coat thickness over the substrate withoutdistortion of the textured surface.

[0033] A typical melt processable polymer resin having the followingformulation was dryblended and compounded in an extruder, achieving amelt at 350° F. to 380° F. Ingredient Weight Percent General PurposeVinyl 66.5 Chloride Resin Methylmethacrylate/Acrylic 1.3 CopolymerProcessing Aid Acrylic Release Agent 0.3 Methylmethacrylate/Acrylic 3.3Copolymer Impact Modifier Fatty Acid Ester Lubricant 0.3 Plasticizer26.0 Stabilizer 2.3

[0034] This melt was introduced into a three roll calender with thefirst calender roll at about 335° F., the second calender roll at about345° F. and the third calender roll at about 355° F.

[0035] A molten layer, nominally 15 mils thick, was formed and applieddirectly to a textured substrate between the third calender roll and arubber pressure roll. The textured substrate was preheated to about 275°F. A second textured multilayer composite was made using the sameprocedure but with a nominally 20 mil thick molten layer.

[0036] Alternatively, a commercially available, 20 mil thick flexiblepolyvinyl chloride film was substituted for the belt processable polymerresin composition formed above. The film was heated around a drum, to atemperature of about 345° F.

[0037] In both cases, the melt processable polymer resin wear layer hada substantially uniform thickness with a variation of less than 25%which followed the contours of the pre-textured substrate. The wearlayer was in intimate contact with the pre-textured substrate; therewere no visible bubbles entrapped between the wear layer and theadjacent surface of the pre-textured substrate, even when the differencein height of the pre-textured surface was at least about 5 mils verticaldistance over no more than about 20 mils horizontal distance.

[0038] While this invention has been described as having a preferreddesign, it is understood that it is capable of further modifications,and uses and/or adaptations of the invention and following in generalthe principle of the invention and including such departures from thepresent disclosure as come within the known or customary practice in theart to which the invention pertains, and as may be applied to thecentral features hereinbefore set forth, and fall within the scope ofthe invention or limits of the claims appended hereto.

1. A textured surface covering comprising: a) a pre-textured substrateand a layer overlying said pre-textured substrate; b) said layercomprising a melt processable polymer resin composition; c) saidpre-textured substrate having a pre-textured surface, d) said layerhaving a first surface adjacent said pre-textured surface and a secondsurface spaced from said ore-textured surface; and e) said layerconforming to said pre-textured surface, whereby the first and secondsurfaces follow the contours of the pre-textured surface.
 2. Thetextured surface covering of claim 1, wherein there are no visiblebubbles entrapped between the first surface of the layer and theadjacent pre-textured surface.
 3. The textured surface covering of claim1, wherein the layer is substantially uniform in thickness.
 4. Thetextured surface covering of claim 1, wherein the thickness of the layervaries less than about 25%.
 5. The textured surface covering of claim 4,wherein the thickness of the layer varies less than about 20%.
 6. Thetextured surface covering of claim 1, wherein the polymer resincomposition comprises a general purpose polyvinyl chloride resin.
 7. Thetextured surface covering of claim 1, wherein the pre-textured substrateis selected from the group consisting of a layer of a woven fibrouslayer, a non-woven fibrous layer, an embossed layer, a layer comprisingdeposited matter and combinations thereof.
 8. The textured surfacecovering of claim 7, wherein the embossed layer is chemically embossed,mechanically embossed, or chemically and mechanically embossed.
 9. Thetextured surface covering of claim 7, wherein the deposited matter isselected from the group consisting of foamable ink, a non-foamable inkand particulate matter.
 10. The textured surface covering of claim 1,wherein the pre-textured surface of the substrate has an area in whichthe difference in height of the pre-textured surface is at least about 1mil vertical distance over no more than about 20 mils horizontaldistance.
 11. The textured surface covering of claim 10, wherein thedifference in height of the pre-textured surface is at least about 2mils vertical distance over no more than about 20 mils horizontaldistance.
 12. The textured surface covering of claim 11, wherein thedifference in height of the pre-textured surface is at least about 5mils vertical distance over no more than about 20 mils horizontaldistance.
 13. The textured surface covering of claim 1, wherein theaverage thickness of the overlying layer is between about 2 mils andabout 50 mils.
 14. The textured surface covering of claim 13, whereinthe average thickness of the overlying layer is between about 5 mils andabout 30 mils.
 15. The textured surface covering of claim 14, whereinthe average thickness of the overlying layer is between about 10 milsand about 20 mils.
 16. The textured surface covering of claim 1, whereinthe viscosity of the melt processable composition during application tothe pre-textured surface of the substrate is from about 4,500 to about70,000 poise.
 17. The textured surface covering of claim 16, wherein theviscosity of the melt processable composition is from about 10,000 to50,000 poise.
 18. The textured surface covering of claim 17, wherein theviscosity of the melt processable composition is from about 13,000 toabout 24,000 poise.
 19. A method of manufacturing a textured surfacecovering having a wear layer bonded thereto comprising the steps of: a)heating a melt processable polymer resin composition to melt or softenthe polymer resin composition; b) applying the melted or softened meltprocessable polymer resin composition to a pre-textured surface of asubstrate, the pre-textured surface having an area with a difference inheight of at least about 1 mil vertical distance over no more than about20 mils horizontal distance; and c) cooling the melt processable polymerresin composition after it is applied to the pre-textured surface toform a bonded wear layer on the pre-textured substrate, the wear layerhaving an average thickness of between about 2 mils to about 50 mils.20. The method of manufacturing a textured surface covering according toclaim 19, wherein the melt processable polymer resin composition isapplied to the pre-textured substrate between a heated roll or drum anda conformable pressure roll.
 21. The method of manufacturing a texturedsurface covering according to claim 19, wherein the melt processablepolymer resin composition is heated on the roll of a calender.
 22. Themethod of manufacturing a textured surface covering according to claim21, wherein the melt processable polymer resin composition is formedinto a layer in a calender prior to being applied to the pre-texturedsurface of the substrate.
 23. The method of manufacturing a texturedsurface covering according to claim 19, wherein the melt processablepolymer resin composition is heated in an extruder.
 24. The method ofmanufacturing a textured surface covering according to claim 19, whereinthe viscosity of the melt processable polymer resin composition is fromabout 10,000 to about 50,000 poises during application to thepre-textured surface.
 25. The method of manufacturing a textured surfacecovering according to claim 24, wherein the viscosity of the meltprocessable polymer resin composition is from about 13,000 to about24,000 poises during application to the pre-textured surface.
 26. Themethod of manufacturing a textured surface covering according to claim19, wherein the average thickness of the wear layer is between about 2mils to about 50 mils.
 27. The method of manufacturing a texturedsurface covering according to claim 26, wherein the average thickness ofsaid wear layer is between about 5 mils to about 50 mils.
 28. The methodof manufacturing a textured surface covering according to claim 27,wherein the average thickness of said wear layer is between about 10mils to about 20 mils.
 29. The method of manufacturing a texturedsurface covering according to claim 19, wherein the pre-textured surfaceof the substrate has an area in which the difference in height of thepre-textured surface is at least about 1 mil vertical distance over nomore than about 20 mils horizontal distance.
 30. The method ofmanufacturing a textured surface covering according to claim 29, whereinthe difference in height is at least about 2 mil vertical distance overno more than about 20 mils horizontal distance.
 31. The method ofmanufacturing a textured surface covering according to claim 30, whereinthe difference in height is at least about 5 mil vertical distance overno more than about 20 mils horizontal distance.
 32. The method ofmanufacturing a textured surface covering according to claim 19 whereinthe melt processable polymer resin composition has a viscosity of fromabout 4,500 to 70,000 poises at the time of application to thepre-textured surface of the substrate
 33. The method of manufacturing atextured surface covering according to claim 19 wherein the meltprocessable polymer resin composition is a general purpose resin.